Project Mercury was
America's first human spaceflight program and the first
major undertaking of the newly created National
Aeronautics and Space Administration (NASA). It proved
that human spaceflight was possible.
A human spaceflight
program had been envisioned even before NASA was formally
established. The U.S. military and the National Advisory
Committee for Aeronautics (NACA), NASA's predecessor, had
debated the best approach to such a program soon after the
Soviet launch of Sputnik I on October 4, 1957. NACA
engineer H. Julian Allen, an expert on problems relating
to the exceedingly great heat generated by vehicles
travelling at high speeds, proposed using a missile to
launch a blunt-shaped spacecraft into orbit. The blunt
shape would dissipate heat and allow for safe re-entry into
the atmosphere. Another NACA engineer, Maxime Faget,
suggested using retrorockets that would slow the vehicle's
speed and cause it to leave orbit, re-enter the atmosphere,
and parachute to an ocean landing. By July 29, 1958, when
President Dwight Eisenhower signed the National
Aeronautics and Space Act that created NASA, a plan to
send humans into space was in place. Its objectives were
to place astronauts in space, test their reactions, and
return them safely to Earth.
The chimpanzee Ham
was the live test subject for the Mercury Redstone 2
flight on January 31, 1961. Here the 17-kg (37-pound)
primate is fitted into a
special biopack couch prior to flight. The 680-kilometer
(420 statute miles)
suborbital mission was a significant accomplishment in the
American route to human spaceflight.
NASA was established on
October 1, 1958, and one week later, NASA formally created
Project Mercury. On December 17, exactly 55 years after
the Wright brothers' first flight, NASA's first
administrator, T. Keith Glennan, announced Project Mercury
to the public.
NASA promptly selected
the astronaut crew. Applicants had to be under 40 years of
age, shorter than 5 feet 11 inches (1.8 meters), in
excellent physical shape, and have a test pilot background
with at least 1,500 hours in the air. From an initial
pool of 508 candidates, NASA winnowed the number down,
finally subjecting 32 to an exhaustive and exhausting
array of physical and psychological tests before selecting
the “Mercury Seven.” Scott Carpenter, L. Gordon Cooper, Jr.,
John H. Glenn, Jr., Virgil I. "Gus" Grissom, Walter M.
Schirra, Jr., Alan B. Shepard, Jr., and Donald K. "Deke"
Slayton were introduced to the public at a Washington,
D.C. press conference on April 9, 1959, and became instant
celebrities and heroes. As the authors of This New Ocean,
a history of Project Mercury, said: “The first seven
American astronauts were an admirable group of individuals
chosen to sit at the apex of a pyramid of human effort.…[They
became a team of personalities as well as a crew of
pilots. They were lionized by laymen and adored by youth
as heroes before their courage was truly tested.”
The greatest challenge to
Mercury engineers was to devise a vehicle that would
protect a human from the temperature extremes, vacuum, and
newly discovered radiation of space. Further, there was
the need to keep an astronaut cool during the burning,
high-speed re-entry through the atmosphere.
The spacecraft that was
designed was cone-shaped with a cylinder on top. It was
6.8 feet (2 meters) long, 6.2 feet (2 meters) in diameter,
and had a 19.2-foot, (5.8-meter) escape tower with a
solid-rocket motor fastened to the cylinder. In a launch
emergency, the rocket would fire and lift the capsule from
an explosion and parachute it into the ocean. With a
volume of only 428.5 cubic feet (12 cubic meters), there
was barely enough room for its pilot, who sat in a
custom-designed couch facing a panel with 120 controls, 55
electrical switches, 30 fuses, and 35 mechanical levers.
The cabin's atmospheric pressure was one-third of that on
Earth and contained pure oxygen.
The blunt end of the
capsule, which would enter the atmosphere first, was
covered with an ablative heat shield to protect it from
the 3000˚ F (1649˚ C) heat of re-entry into the atmosphere.
This shield would burn off and dissipate the heat during
re-entry and descent. Just before the spacecraft impacted
with Earth, the heat shield would detach from the base of
the capsule and release a balloon that would inflate to
cushion the landing. Parachutes would further slow the
The capsule's total
height, including its tower and the rockets attached to
the heat shield, was about 26 feet (8 meters). At launch
it weighed about 17,500 pounds (7,900 kg).
The program used two
different launch vehicles: Redstone rockets, designed by
the rocket team of Wernher von Braun in Huntsville,
Alabama, were used for the suborbital flights. Atlas-D
launch vehicles, modified ballistic missiles, launched the
orbital flights. The Atlas had such a thin skin (to save
weight) that it would have collapsed like a bag but for
its internal pressure.
Eighteen thrusters (small
rockets) operated manually by the astronaut controlled the
spacecraft's attitude (the way it was pointing). Three
retrorockets would fire the capsule out of its orbit and
begin its return to Earth.
Seven suborbital and four
orbital test flights preceded the piloted flights. On one
test flight, in January 1961, a surrogate “passenger,” a
chimpanzee named Ham, was put into a suborbital flight
that reached about 157 miles (253 kilometres) altitude.
Unfortunate Ham experienced much greater acceleration and
gravitational forces during the launch than expected.
Further, a leaky valve resulted in a severe drop in cabin
pressure. When the spacecraft finally splashed down 130
miles (209 kilometres) from its target area, the capsule
began to leak water. Ham survived, and the flight was
The first piloted Mercury
flight lifted off on May 5, 1961, with Alan Shepard behind
the controls of the Freedom 7. (Each astronaut named his
own spacecraft, and a “7” was added to honor the team.)
Reaching a speed of 5,146 miles per hour (8,282 kilometres
per hour) and an altitude of about 116 miles (187
kilometres), Shepard became the first American in space.
He descended safely as the Freedom 7 parachuted into the
Atlantic Ocean at the end of his flight. Although his
suborbital flight lasted only 15 minutes 22 seconds, it
proved that an astronaut could survive and work
comfortably in space, and demonstrated to the 45 million
Americans watching it on TV that the United States had
joined the spaceflight business.
of the Mercury capsule at the end of the second Mercury
mission, July 27, 1961.
In July 1961, Virgil
Grissom's flight in the Liberty Bell 7 resembled Shepard's
until splashdown when its emergency escape hatch
unexpectedly blew off. The capsule flooded and Grissom had
to exit quickly as water poured in. His spacesuit became
waterlogged, and there were a few tense moments before the
helicopter picked him up. His capsule, however, sank,
where it remained at the bottom of the sea until it was
found and retrieved in 1999. It has since been on a “tour”
of museums around the United States.
earth taken by Astronaut John Glenn during his MA-6
spaceflight, February 20, 1962.
John Glenn, Jr. was the
first American to make an orbital flight, travelling three
times around the Earth in his Friendship 7, on February
20, 1962. He was the first American to see a sunrise and
sunset from space and the first photographer in orbit. The
only anxious moments of his flight came before and during
re-entry, when a signal received on the ground indicated
(erroneously, as it turned out) that the capsule's heat
shield had come loose. At one point, Glenn thought his
shield was burning up and breaking away. He ran out of
fuel trying to stop the capsule's bucking motion as it
descended through the atmosphere, but splashed down safely
40 miles (64 kilometres) short of his target. Glenn
returned to Earth a national hero, having achieved Project
Mercury's primary goal.
Glenn is fitted for his space suit prior to lift-off.
Scott Carpenter's flight
on the Aurora 7 in May 1962 was much like Glenn's. He
splashed down 250 miles (400 kilometres) away from his
target, and it took about three hours for the rescue crew
to locate his capsule.
Walter “Wally” Schirra
became the first orbiting television star as he beamed a
telecast back to Earth from his Sigma 7 spacecraft that
October. He set a record: orbiting six times in a mission
that lasted nine hours and 13 minutes.
The final flight in the
series, in May 1963, lasted a record 34 hours/19 minutes,
and circled the Earth 22-1/2 times. The pilot, Gordon
Cooper in his Faith 7, released the first satellite from a
spacecraft-a six-inch (152-millimeter) sphere with a
beacon for testing the astronaut's ability to track
objects visually in space. His mission was so successful
that NASA decided to cancel the final scheduled flight.
astronaut group portrait. Front row, left to right, are
Walter M. Schirra, Jr., Donald K. Slayton, John H. Glenn,
Jr., and M. Scott Carpenter.
Back row, left to right, are Alan B. Shepard, Jr., Virgil
I. Grissom and L. Gordon Cooper
Taken together, the time
in space for the six piloted flights had totalled two days
and six hours. By the time of the last flight, in May
1963, the U.S. space program was looking ahead to its new
goal, announced by President John F. Kennedy only three
weeks after Shepard's suborbital flight, of reaching the
Moon, and by 1963, only 500 of the 2,500 people working at
NASA's Manned Spacecraft Centre in Houston were still
working on Mercury-the remainder was already busy on
Gemini and Apollo.
But Mercury had taken the
critical first step. It had demonstrated that humans could
survive in space, a spacecraft could be designed to launch
them into orbit, and that the crew could return safely to